This invention relates to improvements in a connecting rod and in a method of producing the connecting rod.
In a conventional producing method for a connecting, first a working piece is formed to have a Brinell hardness of not higher than 300 in order to improve machinability and fatigue durability. Thereafter, a portion which will not be subjected to machining is hardened to have a Brinell harness of not lower than 300. This is disclosed in Japanese Patent Provisional Publication No. 59-89720.